<?php
/**
 * Query
 *
 * Free Query Builder / Database Abstraction Layer
 *
 * @package		Query
 * @author		Timothy J. Warren
 * @copyright	Copyright (c) 2012 - 2014
 * @link 		https://github.com/aviat4ion/Query
 * @license		http://philsturgeon.co.uk/code/dbad-license
 */

// --------------------------------------------------------------------------

/**
 * Base Database class
 *
 * Extends PDO to simplify cross-database issues
 *
 * @package Query
 * @subpackage Drivers
 */
abstract class Abstract_Driver extends PDO implements Driver_Interface {

	/**
	 * Reference to the last executed query
	 * @var PDOStatement
	 */
	protected $statement;

	/**
	 * Character to escape indentifiers
	 * @var string
	 */
	protected $escape_char = '"';

	/**
	 * Reference to sql class
	 * @var SQL_Interface
	 */
	public $sql;

	/**
	 * Reference to util class
	 * @var DB_Util
	 */
	public $util;

	/**
	 * Last query executed
	 * @var string
	 */
	public $last_query;

	/**
	 * Prefix to apply to table names
	 * @var string
	 */
	public $table_prefix = '';

	/**
	 * PDO constructor wrapper
	 *
	 * @param string $dsn
	 * @param string $username
	 * @param string $password
	 * @param array $driver_options
	 */
	public function __construct($dsn, $username=NULL, $password=NULL, array $driver_options=array())
	{
		// Set PDO to display errors as exceptions
		$driver_options[PDO::ATTR_ERRMODE] = PDO::ERRMODE_EXCEPTION;
		parent::__construct($dsn, $username, $password, $driver_options);

		// Load the sql class for the driver
		$class = get_class($this)."_sql";
		$this->sql = new $class();

		// Load the util class for the driver
		$class = get_class($this)."_util";
		$this->util = new $class($this);

		// Set additional driver options, if they exist
		if ( ! empty($driver_options) && is_array($driver_options))
		{
			foreach($driver_options as $key => $val)
			{
				$this->setAttribute($key, $val);
			}
		}
	}

	// --------------------------------------------------------------------------
	// ! Concrete functions that can be overridden in child classes
	// --------------------------------------------------------------------------

	/**
	 * Simplifies prepared statements for database queries
	 *
	 * @param string $sql
	 * @param array $data
	 * @return PDOStatement PDOStatement / FALSE
	 * @throws InvalidArgumentException
	 */
	public function prepare_query($sql, $data)
	{
		// Prepare the sql
		$query = $this->prepare($sql);

		// Set the statement in the class variable for easy later access
		$this->statement = $query;

		if( ! (is_array($data) || is_object($data)))
		{
			throw new InvalidArgumentException("Invalid data argument");
		}

		// Bind the parameters
		foreach($data as $k => $value)
		{
			if(is_numeric($k))
			{
				$k++;
			}

			$query->bindValue($k, $value);
		}

		return $query;
	}

	// -------------------------------------------------------------------------

	/**
	 * Create and execute a prepared statement with the provided parameters
	 *
	 * @param string $sql
	 * @param array $params
	 * @return PDOStatement
	 */
	public function prepare_execute($sql, $params)
	{
		$this->statement = $this->prepare_query($sql, $params);
		$this->statement->execute();

		return $this->statement;
	}

	// -------------------------------------------------------------------------

	/**
	 * Returns number of rows affected by an INSERT, UPDATE, DELETE type query
	 *
	 * @return int
	 */
	public function affected_rows()
	{
		// Return number of rows affected
		return $this->statement->rowCount();
	}

	// --------------------------------------------------------------------------

	/**
	 * Quote database table name, and set prefix
	 *
	 * @param string $table
	 * @return string
	 */
	public function quote_table($table)
	{
		// If there isn't a prefix set, just quote the table name
		if (empty($this->table_prefix))
		{
			return $this->quote_ident($table);
		}

		// Split indentifier by period, will split into:
		// database.schema.table OR
		// schema.table OR
		// database.table OR
		// table
		$idents = (array) explode('.', $table);
		$segments = count($idents);

	    // Quote the last item
	    $idents[$segments - 1] = $this->_prefix(end($idents));

	    // Rejoin
	    $table = implode('.', $idents);

		// Finally, quote the table
		return $this->quote_ident($table);
	}

	// --------------------------------------------------------------------------

	/**
	 * Sets the table prefix on the passed string
	 *
	 * @param string $str
	 * @return string
	 */
	protected function _prefix($str)
	{
		// Don't prefix an already prefixed table
		if (strpos($str, $this->table_prefix) !== FALSE)
		{
			return $str;
		}

		return $this->table_prefix.$str;
	}

	// --------------------------------------------------------------------------

	/**
	 * Surrounds the string with the databases identifier escape characters
	 *
	 * @param mixed $ident
	 * @return string
	 */
	public function quote_ident($ident)
	{
		if (is_array($ident))
		{
			return array_map(array($this, __METHOD__), $ident);
		}

		// Handle comma-separated identifiers
		if (strpos($ident, ',') !== FALSE)
		{
			$parts = explode(',', $ident);
			$parts = array_map('mb_trim', $parts);
			$parts = array_map(array($this, __METHOD__), $parts);
			$ident = implode(',', $parts);
		}

		// Split each identifier by the period
		$hiers = explode('.', $ident);
		$hiers = array_map('mb_trim', $hiers);

		// Re-compile the string
		$raw = implode('.', array_map(array($this, '_quote'), $hiers));

		// Fix functions
		$funcs = array();
		preg_match_all("#{$this->escape_char}([a-zA-Z0-9_]+(\((.*?)\))){$this->escape_char}#iu", $raw, $funcs, PREG_SET_ORDER);
		foreach($funcs as $f)
		{
			// Unquote the function
			$raw = str_replace($f[0], $f[1], $raw);

			// Quote the inside identifiers
			$raw = str_replace($f[3], $this->quote_ident($f[3]), $raw);
		}

		return $raw;

	}

	// --------------------------------------------------------------------------

	/**
	 * Helper method for quote_ident
	 *
	 * @param mixed $str
	 * @return mixed
	 */
	public function _quote($str)
	{
		// Don't add additional quotes, or quote numbers
		if (strpos($str, $this->escape_char) === 0 ||
			strrpos($str, $this->escape_char) === 0 ||
			( ! is_string($str) && is_numeric($str))
		)
		{
			return $str;
		}

		return "{$this->escape_char}{$str}{$this->escape_char}";
	}

	// -------------------------------------------------------------------------

	/**
	 * Return schemas for databases that list them
	 *
	 * @return array
	 */
	public function get_schemas()
	{
		return NULL;
	}

	// -------------------------------------------------------------------------

	/**
	 * Return list of tables for the current database
	 *
	 * @return array
	 */
	public function get_tables()
	{
		return $this->driver_query($this->sql->table_list());
	}

	// -------------------------------------------------------------------------

	/**
	 * Return list of dbs for the current connection, if possible
	 *
	 * @return array
	 */
	public function get_dbs()
	{
		return $this->driver_query($this->sql->db_list());
	}

	// -------------------------------------------------------------------------

	/**
	 * Return list of views for the current database
	 *
	 * @return array
	 */
	public function get_views()
	{
		return $this->driver_query($this->sql->view_list());
	}

	// -------------------------------------------------------------------------

	/**
	 * Return list of sequences for the current database, if they exist
	 *
	 * @return array
	 */
	public function get_sequences()
	{
		return $this->driver_query($this->sql->sequence_list());
	}

	// -------------------------------------------------------------------------

	/**
	 * Return list of function for the current database
	 *
	 * @return array
	 */
	public function get_functions()
	{
		return $this->driver_query($this->sql->function_list(), FALSE);
	}

	// -------------------------------------------------------------------------

	/**
	 * Return list of stored procedures for the current database
	 *
	 * @return array
	 */
	public function get_procedures()
	{
		return $this->driver_query($this->sql->procedure_list(), FALSE);
	}

	// -------------------------------------------------------------------------

	/**
	 * Return list of triggers for the current database
	 *
	 * @return array
	 */
	public function get_triggers()
	{
		return $this->driver_query($this->sql->trigger_list(), FALSE);
	}

	// -------------------------------------------------------------------------

	/**
	 * Retreives an array of non-user-created tables for
	 * the connection/database
	 *
	 * @return array
	 */
	public function get_system_tables()
	{
		return $this->driver_query($this->sql->system_table_list());
	}

	// --------------------------------------------------------------------------

	/**
	 * Retrieve column information for the current database table
	 *
	 * @param string $table
	 * @return array
	 */
	public function get_columns($table)
	{
		return $this->driver_query($this->sql->column_list($table), FALSE);
	}

	// --------------------------------------------------------------------------

	/**
	 * Retrieve list of data types for the database
	 *
	 * @return array
	 */
	public function get_types()
	{
		return $this->driver_query($this->sql->type_list(), FALSE);
	}

	// -------------------------------------------------------------------------

	/**
	 * Method to simplify retreiving db results for meta-data queries
	 *
	 * @param string $sql
	 * @param bool $filtered_index
	 * @return mixed
	 */
	public function driver_query($sql, $filtered_index=TRUE)
	{
		// Return if the values are returned instead of a query
		if (is_array($sql))
		{
			return $sql;
		}

		// Return if the query doesn't apply to the driver
		if ($sql === NULL)
		{
			return NULL;
		}

		$res = $this->query($sql);

		$flag = ($filtered_index) ? PDO::FETCH_NUM : PDO::FETCH_ASSOC;
		$all = $res->fetchAll($flag);

		return ($filtered_index) ? db_filter($all, 0) : $all;
	}

	// --------------------------------------------------------------------------

	/**
	 * Return the number of rows returned for a SELECT query
	 *
	 * @see http://us3.php.net/manual/en/pdostatement.rowcount.php#87110
	 * @return int
	 */
	public function num_rows()
	{
		$regex = '/^SELECT\s+(?:ALL\s+|DISTINCT\s+)?(?:.*?)\s+FROM\s+(.*)$/i';
		$output = array();

		if (preg_match($regex, $this->last_query, $output) > 0)
		{
			$stmt = $this->query("SELECT COUNT(*) FROM {$output[1]}");
			return (int) $stmt->fetchColumn();
		}

		return NULL;
	}

	// -------------------------------------------------------------------------
	// ! Abstract public functions to implement in child classes
	// -------------------------------------------------------------------------

	/**
	 * Empty the passed table
	 *
	 * @param string $table
	 * @return void
	 */
	abstract public function truncate($table);

	// --------------------------------------------------------------------------

	/**
	 * Create sql for batch insert
	 *
	 * @param string $table
	 * @param array $data
	 * @return string
	 */
	public function insert_batch($table, $data=array())
	{
		if ( ! is_array($data[0])) return NULL;

		$table = $this->quote_table($table);
		$fields = array_keys($data[0]);

		$sql = "INSERT INTO {$table} (";
		$sql .= implode(',', $this->quote_ident($fields));
		$sql .= ") VALUES ";

		$params = array_fill(0, count($fields), '?');
		$param_string = implode(',', $params);

		// Remove the first array after use, as it is a special case
		$sql .= "({$param_string})";
		$vals = array_values($data[0]);
		array_shift($data);

		// Add another grouping for each
		foreach($data as $group)
		{
			$sql .= ",({$param_string})";
			$vals = array_merge($vals, array_values($group));
		}

		return array($sql, $vals);
	}
}
// End of db_pdo.php